Conversion of hydrogen and carbon monoxide into C1 -C4 range hydrocarbons

Abstract

A process for conversion of hydrogen and carbon monoxide into hydrocarbons in the presence of an ebullient bed of catalyst comprising reduced iron oxide containing an amount of potassium equivalent to 2 to 10 pounds potassium carbonate per 1000 pounds iron oxide catalyst, and having an average particle size in the range of 100-1000 microns. The catalyst may be sulfided for increasing the yield of C 1 -C 4 range hydrocarbons.

We claim: 
     
       1. A process for producing from synthesis gas a stream of light hydrocarbon gases containing an increased yield of C 1  -C 4  range saturated hydrocarbons comprising: (1) reacting hydrocarbons or carbonaceous charge stocks ranging from methane through coal or coke by partial oxidation with a free oxygen-containing gas and H 2  O at an autogenous temperature in the range of about 1600° F. to 3000° F. and a pressure in the range of about 1 to 250 atmospheres in the reaction zone of a noncatalytic synthesis gas generator to produce an effluent gas mixture;   (2) purifying the effluent gas stream from (1), thereby producing a feed gas stream substantially comprising hydrogen and carbon monoxide, and with or without H 2  S, CO 2 , H 2  O and COS;   (3) passing said feed gas stream upward through an ebullient bed of particulate conversion catalyst in a reaction zone at a temperature in the range of about 600° to 1000° F., a pressure in the range of about 200 to 3000 psig, a H 2  +CO space velocity in the range of about 250 to 2500 v/hr/v, a superficial gas velocity in the range of about 1 to 10 ft./sec., and a H 2  /CO mole ratio in the range of at least 1:1 to about 3:1; and wherein said conversion catalyst consists essentially of iron oxide selected from the group consisting of mill scale, magnetite, and mixtures thereof, ground to a particle size in the range of about 350 to 800 microns, magnetically separated from extraneous matter, treated with an aqueous solution of potassium carbonate in an amount sufficient to deposit upon said ground iron oxide about 2-10 pounds potassium carbonate per 1000 pounds iron oxide, dried, chemically reduced with hydrogen at a temperature in the range of about 650°-800° F. and a pressure in the range of about 100 to 1000 psig until evolution of water ceases, and subsequently sulfided at an elevated temperature in the range of about 200°-900° F. with a sulfur-containing compound capable of sulfiding said catalyst such that said reduced iron catalyst contains from about 0.01 to about 0.1 weight percent sulfur;   (4) cooling the effluent gas from the reaction zone to condense out a liquid phase comprising normally liquid hydrocarbons, organic chemicals, and water; and   (5) separating a gas phase comprising light hydrocarbons containing an increased yield of C 1  to C 4  range saturated hydrocarbons, H 2 , CO, H 2  O and CO 2 .   
     
     
       2. The process of claim 1 wherein said reaction temperature in step (3) is in the range of 650°-800° F., wherein said reaction pressure is in the range of 400-1500 psig, wherein said hydrogen plus carbon monoxide space velocity is in the range of about 500-1500 v/hr/v. 
     
     
       3. The process of claim 1 wherein cooled dewatered effluent gas from step (5) is treated in an acid gas absorption process for removal of at least a portion of the carbon dioxide therefrom prior to recycle of said effluent gas to the reaction zone in step (3). 
     
     
       4. The process of claim 1 wherein said potassium promoted reduced iron catalyst is sulfided to a level such that the catalyst contains from about 0.022 to about 0.075 weight percent sulfur. 
     
     
       5. The process of claim 1 wherein said sulfur-containing compound for sulfiding the conversion catalyst in step (3) is H 2  S as present in said feed gas stream from step (2), and said H 2  S is produced in said synthesis gas generator in step (1) from a sulfur-containing hydrocarbon and/or carbonaceous feedstock. 
     
     
       6. The process of claim 1 wherein the feed gas stream that is introduced into the reaction zone in step (3) includes less than 2 mole % of CO 2 . 
     
     
       7. The process of claim 1 provided with the additional steps of recycling to the reaction zone in step (3) about 0.5 to 2 volumes of said gas phase in step (5) optionally removing at least a portion of H 2  O and CO 2  prior to recycle for each volume of fresh feed gas. 
     
     
       8. The process of claim 1 wherein the molar ratio of hydrogen to carbon monoxide in the gas stream from step (1) is increased in the reaction zone in step (3) by the water gas shift reaction. 
     
     
       9. The process of claim 1 wherein the molar ratio H 2  /CO of the effluent gas from the reaction zone in step (3) is greater than that of the feed gas stream entering the reaction zone in step (3).